Levels of evidence

Systematic reviews and

Guidelines

Aboubakr Elnashar Benha University Hospital, Egypt

1

Levels of evidence

2

EBM

requires the integration of the:

• Current best research Evidence with

• Our clinical Expertise and

• Patient’s values, preferences and

circumstances.

3

Three (Es) - EBM Components

4

Level of evidence

I

1 Systematic reviews.

2 One or more large double-blind RCT.

II

1 One or more well-conducted cohort studies.

2 One or more well-conducted case-control studies.

3 uncontrolled experiment.

III Expert opinion.

IV Personal experience

5

6

7

8

9

10

11

RCT:

A group of patients is randomized into

study group & control group.

These groups are followed up for the

variables/outcomes of interest.

If the sample size is large enough,

this study design avoids problems of

bias and confounding variables

12

Randomized Controlled study

13

Searching for the Best Evidence

14

Systematic Review

15

Define A review of a clearly formulated question that

uses systematic & explicit methods to

1. identify, select and critically appraise relevant

research

2. collect & analyse data from the studies that are

included in the review

16

Appraised Topic Topic:

A subject of

discussion or

conversation

Appraise: To evaluate, &

estimate the

quality, amount

of validity, results

and applicability

Critical: careful, exact evaluation

and judgment

Critically

17

Appraise The Evidence (RVRA)

1. Relevance:

It focuses on medical problems common to our practice. patient-oriented evidence

2. Validity:

Correctness (likely to be true)

3. Results:

Clinically important

4. Applicability:

Applicable in and useful for my patients

18

Systematic Review and Meta-analysis

19

Systematic

review

Meta-analysis

Literature

review

Meta-Analysis The use of statistical techniques in a systematic review

to integrate the results of included studies.

20

QUESTION Broad Focused SOURCES/ Usually unspecified Comprehensive; SEARCH Possibly biased explicit SELECTION Unspecified; biased? Criterion-based; uniformly applied APPRAISAL Variable Rigorous SYNTHESIS Usually qualitative Quantitative INFERENCE Sometimes Evidence-based evidence-based

NARRATIVE SYSTEMATIC

Cook, D. J. et. al. Ann Intern Med 1997;126:376-380 21

Why on the Top?

• Meticulous methodology

• Peer reviewed

• Relatively large sample size

• Ensures the highest quality evidence

22

Why do we need it?

• Too much trials

25000 biomedical journals in print

8000 articles published per day

• All studies not equally well designed or interpreted

So, we need a study of studies

• To summarize evidence from studies that address a

specific clinical question.

• To explain differences among studies on the same

question

• To limit bias (rigorous methodology & clear reporting)

23

Model of a Cochrane

systematic review

24

Prof. Archie Cochrane (1909–1988)

Scottish doctor

His book Effectiveness and Efficiency:

Random Reflections on Health Services.

Advocated: use of RCT to make medicine

more effective and efficient:

Cochrane Library database of systematic

reviews

UK Cochrane Centre in Oxford

international Cochrane Collaboration.

25

The Cochrane Collaboration

• International collaboration

• Prepares, maintains, and disseminates

systematic reviews

• Diverse internal structure (Review Groups,

Centres, Fields, Methods Groups, the

Consumer Network)

Cochrane Library

• The current resource with the highest methodological rigor

• $235/year or abstracts only

• www.cochrane.org

26

The logo

represents meta-analysis of 7 trials of IM

corticosteroids given to mothers for

foetal maturation in preterm infants [Chalmers et al].

27

Abstract

Background

Objectives

Criteria for considering studies for this review

Types of participants

Types of intervention

Types of outcome measures

Types of studies

Search strategy for identification of studies

Methods of the review

Description of the studies

Methodological qualities of included studies

Results

Discussion

Conclusions

Implications for practice

Implications for research

Internal sources of support to the review External sources of support to the review

Potential conflict of interest

Acknowledgements

Contribution of Reviewer(s)

Synopsis

Characteristics of included studies

Table 01 results

References to studies included in this review Additional references

Typical Systematic Review “Skeleton”

28

Steps to do a systematic review

• Well-Formulated Question

• Efficient Search Strategies

• Review Abstracts to Determine Eligibility

• Apply Strict Inclusion/Exclusion Criteria

• Extract the Data

• Perform the Required Analyses (Meta-analysis)

• Interpret the Results

• Determine Implications for Health Care Policy and Practice

29

Methodology

• At least 3 reviewers

• Detailed description of :

Trial design characteristics

Why included / excluded

Quality of included studies in details

Source of articles

• Electronic databases

• Bibliography of selected articles

• Hand searching Journals

• “Gray” Literature

• Key Informants

• Web Searching

30

31

What Are CPG?

• Systematically developed statements to assist practitioner decisions about appropriate

healthcare for specific clinical circumstances

E.g.: Guidelines For C.S.

Field MJ, Lohr KN, 1992 32

What they are not… Clinical protocols:

• Rigid statements allowing little or no flexibility or

variation.

• Set out a precise sequence of activities to be

adhered to in the management of a specific

clinical condition.

– Guidelines for management of preeclampsia

– Protocol of MgSO4 for severe preeclampsia

33

The Purpose of CPG

To identify effective:

diagnostic

screening

treatment strategies

Thus improve:

the quality of healthcare

the consumer outcomes.

Decrease variation between practices

34

Types of Guidelines

Consensus Based Guideline:

The most common form

agreement among a group of experts.

Evidence Based Guideline:

Developed after the systematic retrieval

Appraisal of information from the literature

Strength of the evidence.

35

Principles of good guidelines

• Using the best available evidence

• Making recommendations based on evidence

• A multidisciplinary approach which includes

consumers

• Flexibility and adaptability (age, racial, rural,

urban)

• Evaluation and Revision (update 3 -5 years)

36

Different Levels of Guideline Use

• Adopt the guideline (same language/format)

• Keep the text but change the format

• Translate the guideline

• Adapt the guideline (which may include an

update of literature and/or addition of questions)

• Use the guideline as literature (review of

evidence)

37

• Guidelines are usually developed by

• Government agencies

• Institutions

• Professional societies

38

Guideline Development

1. Guideline topic selection

2. Guideline development team formation

3. Purpose & scope of guidelines

4. Identification of key questions

5. Systematic literature review

6. Grading recommendation

7. Consultation and peer reviewing

8. Publication and dissemination

9. Implementation of guidelines

10. Auditing, reviewing and updating 39

Developing Guidelines

• Large investment of resources

• Long time to develop

• Training to bring in specific skills, including

– expertise in guideline development

– skills for searching and evaluating the literature

– leading small group process

– information management 40

It doesn’t have to reinvent the wheel!

It can use ready synthesized EB-guidelines

after modifying them to suite our local needs,

health problems, and economic situations.

41

http://www.nice.org.uk

National Institute for Clinical Excellence (NICE)

42

http://www.sign.ac.uk

The Scottish Intercollegiate Guidelines Network (SIGN)

43

http://www.guideline.gov

National Guidelines Clearinghouse

44

http://www.nzgg.org.nz

New Zealand Guidelines Group

45

http://www.library.nhs.uk/guidelinesfinder

UK NHS National Library of Guidelines

46

Thank You

Aboubakr Elnashar

47